Winged Robotic Cockroach Informs Debate on Evolution of Flight

December 8, 2012 at 9:33 pm

Professor Ronald Fearing and his research team at the University of California, Berkeley, originally intended to create a robot that could navigate all types of terrain. When their first robot DASH, short for Dynamic Autonomous Sprawled Hexapod, fell slightly short of their objective, they decided to attach wings to the robotic cockroach. Only later did they understand that their second version, called DASH+Wings, would further the debate regarding the two major theories on the evolution of flight.

Although DASH+Wings was not able to fly, it consistently outperformed the original DASH over the course of various tests. While DASH could previously climb slopes of at most 5.9°, flapping wings enabled the robot to scale slopes of up to 16.9°. The maximum speed of DASH+Wings was 90% faster than that of its predecessor. The wings also provided the added benefits of preventing the structure from overturning and of allowing the robot to alight on its legs when dropped from a height by increasing the ratio of lift to drag. “Wind tunnel experiments showed that it is aerodynamically capable of gliding at an angle up to 24.7°” (1).

In addition to its numerous practical applications, DASH+Wings offers insight into how flight originally evolved. The “ground-up” theory states that the forerunners of birds developed simple wings that allowed them to move faster on the ground and eventually allowed them to fly. The “trees-down” theory maintains that the predecessors of birds used their crude wings to glide down farther from trees and eventually achieve true flight.

Of these two theories, DASH+Wings supports the latter. In order for the robot to achieve enough lift to rise off the ground, it would hypothetically need to run five times as fast as the original DASH. DASH+Wings was unable to run at even twice the speed of DASH. Nevertheless, flapping wings substantially increased the distance the robot could glide from an elevated point, upholding the “trees-down” theory.

While these observations on the effects of synthetic flapping wings on a hexapod robot do not resolve the debate on the origins of animal flight, it certainly provides useful data with regard to that issue. As Brandon Jackson, an evolutionary biologist at the University of Montana, Missoula, said, “This study is a beautiful example of how relatively simple bioinspired robots can address [questions] that are difficult or impossible to test in living organisms” (2).